This invention relates to a method for fitting magnetic wedges used in the stator slots of an electric rotary machine and an apparatus therefor.
It is generally known that magnetic wedges are used in the stator slots of electric rotary machines, especially large-capacity electric rotary machines. These magnetic wedges, however, are less frequently used in low-voltage, small-capacity electric rotary machines. The reason is that irregularly wound coils are used for the windings with semi-enclosed stator slots which are widely used in the low-voltage, small-capacity electric rotary machines. That is, with the stator slots of this type, the shape and size of coil sides contained therein are not fixed, so that even magnetic wedges of a fixed configuration cannot be held in any fixed positions in the stator slots, often getting too deep into the slots or projecting outside. This will result in variations of the flux distribution in the air gap of the electric rotary machine for each slot. Such result has an awkward effect on the primary object of the use of the magnetic wedges, that is, the object to decrease the difference between the maximum value and minimum value of the flux distribution in the air gap of the electric rotary machine to reduce higher harmonics caused in the core and thereby to reduce the iron loss of the rotary machine by disposing magnetic wedges made of material with a proper permeability in the proper position of the slot openings of the stator slots. Accordingly, there is a demand for the appearance of a method and apparatus to eliminate such awkward effect.